GM Introduces All-New Duramax 8.3L Turbo-Diesel V-8 for Heavy-Duty Trucks

General Motors unveiled updates for its new 2027 heavy-duty truck lineup, which will launch this year on the Chevrolet Silverado HD and GMC Sierra HD. Central to the updates are GM’s first all-new, in-house-designed heavy-duty Duramax 8.3L Turbo-Diesel V-8 engine option, segment-first rack-and-pinion Electric Power Steering (EPS) and a new electronic brake-boost architecture.

“For 2027, we took GM’s proven HD validation playbook and turned up the capability—integrating new powertrain, braking, steering and chassis technologies for serious customers who push their trucks hard every day,” said Mark Dickens, executive chief engineer for GM full-size trucks and SUVs. “HD customers don’t hold back—and neither did we.”

New 8.3L Diesel & Updated 6.6L Gas V-8

The all-new Duramax 8.3L Turbo-Diesel is GM’s first clean-sheet HD V-8 designed, developed and manufactured in-house for heavy-duty pickup applications. Key benefits include:

• All-new, GM-developed HD diesel architecture, designed specifically around heavy-duty pickup customers, with a compacted graphite iron cylinder block and fully forged crankshaft, connecting rods and steel pistons forming the foundation for strength and durability.
• More confident power and towing, with 555 horsepower and 1,230 pound-feet of torque, supported by a broad torque curve, high-flow fuel injection and vehicle integration focused on launching heavy trailers, climbing grades and maintaining control under load.
• Advanced cooling and turbocharging systems built for towing, including a compact dual-stage air-to-water charge cooling system, high-efficiency variable-geometry turbocharger and upgraded engine-cooling strategy to help deliver consistent performance.
• Improved refinement and drivability, with the new engine architecture, integrated intake design, advanced combustion system and crankshaft isolation hardware helping reduce noise and vibration while supporting a more confident HD driving experience.
• Integrated diesel system engineered as a complete package, pairing the engine with the Allison 10-speed transmission, upgraded exhaust braking capability and a new aftertreatment layout designed to support heavy-duty performance, regeneration functionality and customer confidence over long-distance towing.

“This new diesel engine is the culmination of decades of GM diesel development and integration,” said Norman Peralta, executive chief engineer, Global Engine and Battery Systems. “From the clean-sheet architecture and combustion system to the cooling, aftertreatment and transmission calibration, this is a powertrain built with heavy-duty purpose and pride.”

The new engine will be built at GM’s expanded DMAX facility in Brookville, Ohio, a 1.4-million-square-foot plant that brings machining and assembly for the engine together under one roof. GM had previously invested $920 million to grow the DMAX to handle this high-volume engine program, the release noted.

The standard, enhanced 6.6L gas V-8, assembled at GM’s Tonawanda Engine Plant in New York, now delivers 412 horsepower and 472 pound-feet of torque, with improved low-end pull and updated emissions hardware supported by a new Turbo-Jet intake manifold, revised lubrication system, engine-mounted oil cooler and digital oil-level display.

Both the new diesel and updated 6.6L gas V-8 are paired with the Allison 10-speed 10L1000 transmission and advanced shift logic to help keep each engine in its optimal range for smoother acceleration, stronger grade performance and more confident control with heavy trailers, the company said.

Segment-First Electric Power Steering for HD Trucks

For 2027, GM’s HD pickups move to an all-new rack-and-pinion Electric Power Steering system—a segment-first for heavy-duty trucks, replacing the previous hydraulic-assisted steering system with an all-new Electric Power Steering architecture designed specifically for heavy-duty truck demands, officials stated.

The Electric Power Steering system helps to deliver:

• Higher steering output with approximately 30% more power than the current HD hydraulic steering gear to support heavy front-axle loads, low-speed maneuvering, towing and demanding work-truck use.
• More precise, consistent steering in demanding conditions, with expanded drive-mode tuning, improved on-center feel and reduced kickback.
• A cleaner, quieter and lower-maintenance system, eliminating hydraulic pumps, hoses, fluid and related hardware to reduce traditional steering noise and lower system complexity.
• HD-grade durability and protection, with built-in system redundancy plus corrosion- and impact-resistant hardware designed for harsh heavy-duty truck environments, including rough terrain, road debris and severe-duty use.
• Independent functionality: electric steering allows full steering assist capability regardless of engine speed or brake assist utilization, helping to optimize vehicle maneuverability and performance for driver confidence.

Together, the new EPS system provides GM’s HD trucks a modern steering foundation that is stronger, quieter and more precisely tuned. From tight low-speed maneuvers and heavy towing to rough roads and off-road terrain, the system is designed to help drivers feel more connected, more in control and more confident behind the wheel, according to GM.

Electronic Brake-Boost & Upgraded HD Brake Hardware

Featuring a segment-first electronic brake-boost system in a heavy-duty pickup, GM is introducing modern brake technology to the HD segment. Benefits include:

• First-ever electronic braking for an HD pickup, designed for heavy-duty capability and control.
• Stronger, more consistent stopping performance, with larger 14.6-inch front rotors, new four-piston fixed front calipers and upgraded rear hardware that help improve thermal capacity, brake pedal stiffness and braking confidence with big trailers.
• More linear, predictable pedal feel, with reduced pedal travel, a new pedal position and a refined pedal feel make braking feel smoother.
• Smarter braking integration, supporting advanced driver-assistance features like Adaptive Cruise Control and Automatic Emergency Braking, while enhanced diagnostics help detect conditions such as brake fade or leaks sooner.
• Cleaner, lighter and more refined system architecture, eliminating the shared hydraulic source for steering and braking to reduce complexity, remove weight, improve low-speed steering feel and support more consistent brake-control tuning on pavement and off-road.

Together, the new brake system gives GM’s HD trucks a modern, confidence-inspiring braking foundation—one that reacts more precisely and works seamlessly with the truck’s steering, chassis and driver-assistance technologies, the company said.

Tow/Haul, Off-Road & New Terrain Drive Modes

The 2027 HD lineup expands GM’s coordinated drive-mode strategy, so powertrain, steering, braking and chassis systems respond together to towing, hauling, highway driving and off-road demands. Available modes include:

• Normal – Everyday calibration for commuting and unloaded driving.
• Tow/Haul – Tailors engine mapping, shifting, exhaust brake, grade-braking, EPS assist and electronic brake-boost tuning to support heavy towing and hauling with more stability and control.
• Off-Road – Adjusts ABS, traction control and stability control to allow more wheel slip and side slip on loose surfaces, supported by EPS and eBoost tuning that cuts harsh feedback.
• New Terrain Mode (ZR2 / AT4X), a first for GM’s HD trucks, enabling one-pedal off-road driving in 4HI and 4LO; lifting off the accelerator automatically applies braking for precise control on steep grades and technical obstacles.

Up to 38,000 Pounds of Max Trailering

GM says the 2027 HD models are engineered to offer serious towing, with capability of up to 46,500 pounds GCWR and up to 38,000 pounds max trailering on select configurations. Core updates include:

• Higher max available trailering capability, with properly equipped models offering up to 38,000 pounds max trailering and every diesel dually model capable of towing up to an available 30,000 pounds or more.
• More confidence with heavy loads, with revised chassis, suspension, steering and braking systems tuned together to help the truck feel stable, predictable and controlled when towing at or near maximum ratings.
• Powertrains built to pull, pairing the available all-new Duramax 8.3L Turbo-Diesel V-8 and enhanced 6.6L gas V-8 engines with the Allison 10-speed transmission and updated shift strategies to help launch heavy trailers, climb grades and manage downhill control.
• Available visibility technology for easier towing, including up to 14 available camera views such as Transparent Trailer View, Bed View and Surround Vision to help with hitching, lane changes, reversing and trailer monitoring.
• Integrated trailering support from setup to the road, with the available in-vehicle trailering app, available Trailer Side Blind Zone Alert and available trailer tire pressure and temperature monitoring helping drivers prepare, connect and stay aware while towing.

The 2027 HD lineup is engineered to make heavy towing feel easier, smarter and more secure—combining added capability with integrated technologies that help drivers hitch, maneuver, climb, descend and tow big loads with greater confidence, according to the release.

Availability

The 2027 Chevrolet Silverado HD and GMC Sierra HD are expected to arrive at U.S. dealers beginning late 2026. MSRP and additional product information will be announced in future updates.